JP6427862B2 - Dust core, manufacturing method thereof, inductance element using the dust core, and rotating electric machine - Google Patents

Description

  The present invention relates to a dust core, and more particularly to a dust core using an amorphous alloy powder and a method for manufacturing the same. The present invention also relates to an inductance element and a rotating electrical machine using the dust core.

  Due to heightened awareness of environmental protection and energy saving, eco-products (for example, solar power generation, hybrid vehicles, electric vehicles, etc.) have begun to spread widely. In these eco-products, DC-DC converters and inverters are used for high efficiency, and in the converters and inverters, inductance elements (voltage components and current fluctuation (AC components and noise components) prevention) For example, a reactor and a choke coil) are mounted. Further, in rotating electrical machines such as motors, it is known that the magnetic characteristics of the stator and rotor cores have a large effect on the efficiency of the rotating electrical machines.

  For eco-products, miniaturization of all parts is one of the most important issues. In order to meet the demand for downsizing the inductance element, the importance of a dust core having a high degree of freedom in shape is increasing with respect to the magnetic core used. In order to increase the efficiency of converters and inverters, powder magnetic cores used for inductance elements are required to have high magnetic properties and high mechanical strength. Further, by using a dust core having high magnetic properties as a stator core or rotor core of a rotating electrical machine, it is possible to reduce the size and increase the efficiency of the rotating electrical machine.

  Here, the dust core is a magnetic core obtained by press-molding a soft magnetic metal powder whose surface is electrically insulated. Conventionally, soft magnetic metals include Fe (pure iron), Fe-Si (iron-silicon) based alloys, Fe-Si-Al (iron-silicon-aluminum) based alloys, Fe-Ni (iron-nickel) based. Metal materials such as alloys have been used. Amorphous metal (amorphous alloy) with ferromagnetic elements (Fe, Ni, Co (cobalt), etc.) as the main component has excellent magnetic properties (for example, high saturation magnetic flux density, high magnetic permeability, It has been expected as a magnetic core material because of its low iron loss). Among them, Fe-Si-B (iron-silicon-boron) -based amorphous metals have attracted attention in recent years.

  Amorphous metals are generally produced by ultra-quenching a molten alloy (for example, a single roll liquid quenching method, a super-quenching water atomizing method). Amorphous metals have advantages such as toughness, high corrosion resistance, and soft magnetism, but also have the disadvantage of being inferior in moldability because they are very hard and difficult to plastically deform. For this reason, various techniques for improving the moldability have been studied in order to apply amorphous metal powder to a dust core.

  For example, in Patent Document 1 (Japanese Patent Laid-Open No. 2010-141183), two or more types of amorphous soft magnetic alloy powders having different average particle sizes and softening points are lower than the crystallization temperature of the amorphous soft magnetic alloy powder. Mix with melting point glass powder (bismuth glass or phosphate glass), then coat with binder insulating resin, mix with lubrication resin, and then press mold to make molded body, then mold A dust core is disclosed in which an annealing treatment at a temperature lower than the crystallization temperature of the amorphous soft magnetic alloy powder is performed on the body in the air. According to Patent Document 1, the surface of the amorphous soft magnetic alloy powder is oxidized by the annealing treatment, and the binding strength between the low melting point glass and the soft magnetic alloy powder is increased. It is said that it is possible to provide a dust core excellent in mechanical strength.

  On the other hand, due to demands for high performance and miniaturization of inductance elements (for example, reactors, choke coils), high density and high strength are also required for dust cores. In order to meet such requirements, an amorphous metal that exhibits a supercooled liquid state in a wide temperature range (glass transition is clearly observed) with the aim of improving the formability of the amorphous metal itself in a powder magnetic core using amorphous metal. Various technologies using amorphous metals have been developed.

For example, Patent Document 2 (Japanese Patent Application Laid-Open No. 2002-184616) discloses supercooling represented by the equation: ΔT _x = T _x −T _g (where T _x is the crystallization start temperature and T _g is the glass transition temperature). The temperature interval ΔT _{x of the} liquid is 20 K or more, and includes one or both of elements X of Al and Ga, one or more elements Q of P, C, Si, and B, and Fe A metallic glass alloy powder composed of an amorphous phase as a main phase is added with a binder composed of a silicone elastomer and a lubricant composed of aluminum stearate and is solidified by heating. A dust core is disclosed. According to Patent Document 2, metallic glass alloy powders are easily slidable with each other during compression molding, and the relative density of the powder magnetic core can be improved while relaxing the stress and strain inside the powder magnetic core. It is said that a dust core having a high magnetic permeability and a low iron loss can be formed without causing phase precipitation.

In Patent Document 3 (Japanese Patent Laid-Open No. 2009-120927), the composition excluding inevitable impurities is represented by the composition formula: (Fe _1-a M _a ) _100-wxyz Si _w B _x C _y L _z , Among the constituent elements of the composition formula, M is one or more elements selected from Co and Ni, L is one or more elements selected from Al, Cr and Mo, and 0 ≦ a ≦ 0.3, 4 atom% ≦ w ≦ 10 atom%, 10 atom% ≦ x ≦ 18 atom%, 1 atom% ≦ y ≦ 7 atom%, 0.3 atom% ≦ z ≦ 5 atom% A temperature difference ΔT _x (ΔT _x = T _x −T _g ) between the crystallization start temperature T _x and the glass transition temperature T _g is 20 ° C. or more, and the saturation magnetic flux density is 1.2 T or more. There is disclosed a soft magnetic amorphous alloy characterized in that it is. Also disclosed is a dust core formed by molding a mixture containing the soft magnetic amorphous alloy powder and a binder. According to Patent Document 3, since the soft magnetic amorphous alloy is excellent in amorphous forming ability, an amorphous phase is formed even when the cooling rate is not so high (about 10 ³ ° C / second). In addition, since the amorphous structure is highly uniform, it has no magnetic anisotropy and has excellent soft magnetic properties. Furthermore, a dust core using the soft magnetic amorphous alloy powder is said to be suitable for downsizing.

JP 2010-141183 A JP 2002-184616 A JP 2009-120927 A

  As described above, since amorphous metal is very hard and hardly plastically deforms at room temperature, a very high molding pressure (for example, 1500 to 2000 MPa) is required to increase the density of the green compact. However, there is a problem that a high molding pressure increases the cost of a press molding apparatus and a mold required for the molding pressure and increases the manufacturing cost of the dust core. Further, even when such a high forming pressure is applied, it is extremely difficult to plastically deform the amorphous metal at room temperature, so that the relative density (the space factor of the amorphous metal) remains at most 80%.

  The dust core described in Patent Document 1 is said to be able to provide a dust core with excellent mechanical strength even when low pressure molding is performed at room temperature, but requires a molding pressure of 1300 MPa. Absolutely high enough pressure. In addition, the density of the dust core is not increased despite being molded at a high pressure, and as a result, it cannot be said that the mechanical strength of the dust core is sufficiently high. If the mechanical strength of the dust core is insufficient, the dust core may be damaged in the winding process when the inductance element is manufactured.

  On the other hand, in the powder magnetic cores described in Patent Document 2 and Patent Document 3, since heat molding is performed using metal glass, the moldability is good and the density can be increased relatively easily. However, magnetic properties (high magnetic permeability, low coercive force, high magnetic flux density, etc.) important as soft magnetic materials tend to be inferior to metallic glass compared to Fe-Si-B amorphous metals. This is because a large amount of an additive element other than the ferromagnetic element is added to obtain a wide supercooled liquid region in the metal glass. Further, even if a high-density molded body is made of metal glass, there are problems such as a decrease in insulation between the powders and damage to the molded body during the removal from the mold. This is because the supercooling temperature region of the metallic glass is a high temperature of 400 ° C. or higher, and lubrication between the mold and the sample becomes difficult.

  In recent years, demands for higher efficiency, higher output, smaller size, and lower cost for eco-products are increasing, and the demand for each component used in eco-products is also getting stronger. For this reason, conventional powder magnetic cores cannot meet various requirements.

  Accordingly, an object of the present invention is to use a Fe-based amorphous metal powder having excellent magnetic properties in order to satisfy these requirements, and further increase the density of the dust core (for example, the space factor of amorphous metal 80 To provide a dust core having excellent magnetic properties and high mechanical strength. Moreover, it is providing the method of manufacturing such a powder magnetic core at low cost. Furthermore, it is providing the inductance element and rotary electric machine which satisfy | fill the request | requirement requested | required of an eco-product component by using the said powder magnetic core.

According to one aspect of the present invention, there is provided a powder magnetic core mainly composed of Fe (iron) based amorphous metal powder and a resin binder, the crystallization temperature T _x ( K, Kelvin) and the melting point T _m (K) of the resin binder is “T _m / T _x ≧ 0.70”, and the Fe-based amorphous metal powder is plastically deformed in the warm forming, Provide a dust core whose space factor is more than 80% and less than 99%.

The present invention is also a method for producing a powder magnetic core mainly composed of a Fe-based amorphous metal powder and a resin binder, the resin coating step of coating the resin binder on the particle surface of the Fe-based amorphous metal powder; , A warm forming step of forming a molded body at a predetermined temperature and pressure on the Fe-based amorphous metal powder coated with the resin binder, and alleviating strain accumulated in the Fe-based amorphous metal powder in the molded body The relationship between the crystallization temperature T _x (K, Kelvin) of the Fe-based amorphous metal and the melting point T _m (K) of the resin binder is “T _m / T _x ≧ 0.70”. The predetermined temperature in the warm forming step is more than 0.75 and not more than 0.95 of the crystallization temperature, the predetermined pressure is 500 MPa or more and 1000 MPa or less, and the Fe-based amorphous metal powder in the formed body Provided is a method for producing a dust core having a space factor of 80% or more and 99% or less.

  According to the present invention, the Fe-based amorphous metal powder having excellent magnetic properties is used, and the powder particles are plastically deformed while maintaining the insulation between the Fe-based amorphous metal powder particles when compacted. Therefore, it is possible to realize higher density than conventional (for example, the space factor of amorphous metal exceeds 80%). As a result, a dust core having excellent magnetic properties and high mechanical strength can be provided. Moreover, the method of manufacturing such a powder magnetic core at low cost can be provided. Furthermore, by using the dust core, an inductance element and a rotating electrical machine that satisfy the requirements for eco-product parts can be provided.

It is a perspective schematic diagram which shows an example (choke coil) of the inductance element which concerns on this invention. It is a perspective schematic diagram which shows another example (reactor) of the inductance element which concerns on this invention. 2 is a time-temperature chart and a time-forming pressure chart in a warm forming step (forming temperature 533 K). 4 is a time-temperature chart and a time-forming pressure chart in a warm forming step (forming temperature 693 K). It is a SEM observation image which shows the used Fe group amorphous metal powder (before warm forming). It is a SEM observation image which shows an example of the cross-sectional structure of the produced powder magnetic core. 4 is a graph showing the relationship between the space factor of Fe-based amorphous metal and the molding temperature in the dust core of Experiment 1.

(Basic idea of the present invention)
When the sphere is a true sphere that is not deformed, the upper limit is theoretically about 78% even if the sphere diameter distribution is optimally controlled. In order to increase the space factor (relative density) of the amorphous metal in the dust core, it is desirable in principle to plastically deform the amorphous metal particles themselves to increase the filling rate (space factor) of the amorphous metal particles.

Amorphous metal particles may be plastically deformed by compacting in a temperature region near the crystallization temperature (T _x ). For example, in Patent Document 2, a mixture of metallic glass alloy powder (spherical particles), a binder, and a lubricant is heated to a predetermined temperature and compression molded. According to Patent Document 2, the density of the powder magnetic core is increased by adding a predetermined amount of lubricant as compared with the case where no lubricant is added.

  However, when the density is converted to the space factor (relative density) of the metallic glass alloy, it is considered to be less than 80%, and the metallic glass alloy powder particles themselves are not considered to be plastically deformed (if the metallic glass alloy powder particles Is sufficiently plastically deformed, the relative density is considered to greatly exceed the theoretical filling rate of the true sphere). In other words, it can be considered that the result of Patent Document 2 indicates the difficulty of plastically deforming amorphous metal particles in the dust core.

  On the other hand, in the dust core, it is necessary to electrically insulate each particle to be dust-molded in order to reduce eddy current loss. Therefore, compaction molding is performed by forming a layer that serves as both interparticle lubrication and electrical insulation on the surface of the amorphous metal particles.

  In general, resin binders (for example, epoxy resins, phenol resins, acrylic resins) are excellent in lubricity and electrical insulation even with thin coatings, and have the advantage of minimizing the volume of objects other than amorphous metal particles, There is a weak point in which the warm press temperature is restricted from the viewpoint of safety (in other words, it is difficult to plastically deform the amorphous metal particles because the warm press temperature cannot be raised sufficiently). Inorganic binders (for example, oxide powders) have the advantage of sufficiently increasing the warm press temperature because of their excellent heat resistance, but a certain amount of thickness is required to ensure lubricity and electrical insulation, There is a weak point in terms of improving the space factor of amorphous metal particles. That is, in the prior art, a solution that satisfies all the requirements (space factor, lubricity, and electrical insulation) has not been found.

Therefore, the present inventors can use a Fe-based amorphous metal powder having excellent magnetic properties, increase the density of the powder magnetic core than before, and ensure electrical insulation between the powder particles even after compacting. We have intensively studied the means. As a result, Fe-based amorphous metal the crystallization temperature T _x (K, Kelvin) relationship T _m / T _x of the melting point T _m (K) of the resin binder is more than the predetermined value _{(T m / T x ≧ 0.70} ) We selected a Fe-based amorphous metal and a resin binder so as to achieve a solution, and found one solution to control the warm press temperature. The present invention is based on this finding.

As described above, the powder magnetic core according to the present invention is a powder magnetic core mainly composed of an Fe-based amorphous metal powder and a resin binder, and is formed by warm forming, and the crystallization temperature of the Fe-based amorphous metal. The relationship between T _x (K) and the melting point T _m (K) of the resin binder is “T _m / T _x ≧ 0.70”, and the Fe-based amorphous metal powder is plastically deformed in the warm forming. The space factor is more than 80% and 99% or less. Assuming that the amorphous metal particles to be compacted are almost spherical, it can be considered that plastic deformation occurs in at least part of the amorphous metal particles when the space factor exceeds 80% in the compact. The space factor is more preferably 82% or more, and still more preferably 85% or more, from the viewpoint of the magnetic properties and mechanical properties of the dust core.

The present invention can add the following improvements and changes to the above-described powder magnetic core according to the present invention.
(I) The crystallization temperature T _x of the Fe-based amorphous metal is 823 K or less, and the melting point T _{m of the} resin binder is 533 K or more.
(Ii) The Fe-based amorphous metal is an Fe—Si—B (iron-silicon-boron) amorphous metal, and the resin binder is any one of polyether ether ketone, polyphenylene sulfide, and polyamide 66.

  According to another aspect of the present invention, the inductance element according to the present invention is an inductance element using a powder magnetic core, and at least a part of the powder magnetic core is the powder magnetic core according to the present invention. It is characterized by being.

The present invention can add the following improvements and changes to the above-described inductance element according to the present invention.
(Iii) The inductance element is a reactor or a choke coil.

  According to still another aspect of the present invention, the rotating electrical machine according to the present invention is a rotating electrical machine using a dust core, wherein at least a part of the dust core is the above-described dust core according to the present invention. It is characterized by being.

The present invention can add the following improvements and changes to the rotating electrical machine according to the present invention.
(Iv) The dust core is a stator core and / or a rotor core.

In addition, as described above, the method for manufacturing a powder magnetic core according to the present invention is a method for manufacturing a powder magnetic core mainly composed of an Fe-based amorphous metal powder and a resin binder, A resin coating step of coating the resin binder on the particle surface, a warm molding step of forming a molded body at a predetermined temperature and pressure on the Fe-based amorphous metal powder coated with the resin binder, and the molding A strain relaxation heat treatment step for relaxing strain accumulated in the Fe-based amorphous metal powder in the body, and a crystallization temperature T _x (K) of the Fe-based amorphous metal and a melting point T _m (K) of the resin binder, The relationship of “T _m / T _x ≧ 0.70”, the predetermined temperature in the warm forming step is more than 0.75 0.95 or less of the crystallization temperature, and the predetermined pressure is 500 MPa or more and 1000 MPa or less. Yes, the molded body Wherein the space factor of definitive the Fe-based amorphous metal powder is less than 80% 99%. The space factor is more preferably 82% or more, and still more preferably 85% or more.

The present invention can add the following improvements and changes in the method of manufacturing a dust core according to the present invention.
(V) The Fe-based amorphous metal is an Fe-Si-B amorphous metal, and the resin binder is any one of polyether ether ketone, polyphenylene sulfide, and polyamide 66.
(Vi) The heating in the warm forming step and / or the strain relaxation heat treatment step is performed by microwave heating.

  Hereinafter, an embodiment according to the present invention will be described in detail along a manufacturing procedure. However, the present invention is not limited to the embodiments taken up here, and can be appropriately combined and improved without departing from the technical idea of the present invention.

(Dust core and manufacturing method thereof)
As described above, in the dust core according to the present invention, the relationship between the crystallization temperature T _x (K) of the Fe-based amorphous metal and the melting point T _m (K) of the resin binder is “T _m / T _x ≧ 0.70”. The Fe-based amorphous metal and the resin binder are selected so that In the present invention, amorphous metal is defined as including an amorphous material expressed as “metallic glass”.

Generally, the range of the crystallization temperature T _x is approximately from 723 to 1023 K Fe-based amorphous metal (about 450 to 750 ° C.), softening point becomes possible plastic working is about five hundred and seventy-three to eight hundred seventy-three K (approximately 300 to 600 ° C. ). Softening point depends on the crystallization temperature T _x, often in the 100 to 130 K lower temperature crystallization temperature T _x. That is, the lower the crystallization temperature T _x Fe-based amorphous metal, it is possible to plastic working at low temperatures. For example, plastic processing is possible from about 593 to 623 K for Fe-based amorphous metals with a crystallization temperature T _x of 723 K, and plastic processing from about 893 to 923 K for Fe-based amorphous metals with a crystallization temperature T _x of 1023 K Is possible.

If the combination of the Fe-based amorphous metal and the resin binder has a relationship of “T _m / T _x ≧ 0.70”, the Fe-based amorphous metal particles are not thermally degraded at the molding temperature of the dust core without the resin binder being thermally deteriorated. It can be plastically deformed. As a result, a dust core having excellent magnetic properties and high mechanical strength can be obtained. When the combination of the Fe-based amorphous metal and the resin binder has a relationship of “T _m / T _x <0.70”, it becomes difficult to achieve both the plastic deformation of the Fe-based amorphous metal particles and the prevention of thermal deterioration of the resin binder. In consideration of the melting point of the resin binder, the upper limit of “T _m / T _x ” is considered to be about 0.85.

If the resin binder that electrically insulates the amorphous metal particles in the dust core is thermally degraded, the eddy current loss of the dust core increases significantly, so the Fe-based amorphous metal selected can be crystallized so that it can be plastically deformed at the lowest possible temperature. low amorphous metals temperature T _x is preferable. For example, the crystallization temperature T _x of the Fe-based amorphous metal is preferably not more than 823 K, more preferably at most 743 K. As such an Fe-based amorphous metal, the Fe-Si-B system is particularly preferred because it exhibits excellent magnetic properties (high saturation magnetic flux density, high magnetic permeability, very low iron loss). For example, Fe-Si-B -Cr-C amorphous metal, Fe-Si-B-Co amorphous metal, Fe-Si-B-Cu-Nb amorphous metal can be used. More specifically, 2605HB1 (Metglas, Inc., T _x = 739 K) crushed powder and atomized powder of the same composition, 2605SA1 (Metglas, Inc., T _x = 763 K) crushed powder and the same composition Atomized powder or KUAMET (registered trademark, Epson Atmix Co., Ltd., T _x = 813 K) can be preferably used.

  Although there is no particular limitation on the powder particle diameter of the Fe-based amorphous metal, the average particle diameter is preferably 10 μm or more and 200 μm or less for a dust core.

The resin binder to be selected preferably has high heat resistance so as not to be thermally deteriorated at the molding temperature of the dust core. As such a resin binder, for example, polyether ether ketone (PEEK, T _m = 613 K), polyphenylene sulfide (PPS, T _m = 563 K) or polyamide 66 (PA66, T _m = 538 K) is preferably used. Can be used. In particular, PEEK is preferable because it has high heat resistance and exhibits excellent sliding characteristics and mechanical strength.

  As a manufacturing method, first, a selected Fe-based amorphous metal powder and a resin binder are mixed, and a resin coating process is performed in which the resin binder is coated on the particle surface of the Fe-based amorphous metal powder. The mixing volume ratio of the Fe-based amorphous metal powder and the resin binder is preferably “85:15” to “99: 1”. If the volume ratio of the resin binder exceeds 15% by volume, the plastic deformation of the Fe-based amorphous metal particles may be hindered, and the dust core may not be sufficiently densified, and the effect of improving magnetic properties may not be obtained. If the volume ratio of the resin binder is less than 1% by volume, the resin binder may be too small to make electrical insulation between the amorphous metal particles difficult.

  The mixing / resin coating method is not particularly limited, and a known method (for example, a mechanical mixing method) can be used.

  Next, a warm forming process is performed in which the Fe-based amorphous metal powder coated with the resin binder is hot pressed at a predetermined temperature and pressure to form a compact. The warm forming step of the present invention comprises a step of applying pressure before raising the temperature, unloading and cooling after raising and holding the temperature.

The molding temperature T is preferably “0.75T _x <T ≦ 0.95T _x ”. As described above, the amorphous metal may be plastically deformed by applying a stress in the temperature region near the crystallization temperature (T _x ). Therefore, a high-temperature tensile test was performed on the aforementioned 2605HB1 and 2605SA1.

  The high temperature tensile test was performed as follows. First, electric discharge machining was performed on an amorphous metal ribbon (thickness 0.025 mm) prepared in advance, and a test piece having a dumbbell shape (parallel portion dimensions 50 mm × 12.5 mm × 0.025 mm) was cut out. As the high-temperature tensile test conditions, a universal testing machine (manufactured by Shimadzu Corporation) is used, and the target temperature is set in the range of room temperature to 693 K in the air atmosphere. / min) started.

As a result of the high-temperature tensile test, each specimen started plastic deformation around a temperature of “0.75 T _x ”. From the results of this high-temperature tensile test, it is considered that the Fe-based amorphous metal particles are difficult to be plastically deformed when the molding temperature T is “T ≦ 0.75T _x ”. On the other hand, when the molding temperature T becomes “0.95T _x <T”, some Fe-based amorphous metal particles may start to crystallize. The molding temperature T is preferably not less than the temperature just below the melting point of the resin binder (for example, T _m −10 K) and less than the thermal decomposition temperature.

  There is no particular limitation on the heating method in the molding process, and a known method can be used. However, it is more preferable to use microwave heating with an electromagnetic wave of 300 MHz to 300 GHz. Amorphous metal particles are plastically deformed mainly in the surface area of the particles. Microwave heating can simultaneously and preferentially heat the surface region of each Fe-based amorphous metal particle, and thus contributes to shortening the temperature rise time (that is, reducing the manufacturing cost). In addition, overheating of the resin binder (excess heat input to the resin binder) can be suppressed as compared to radiant heating.

  The molding pressure is preferably 500 MPa or more and 1000 MPa or less. When the molding pressure is less than 500 MPa, the plastic deformation of the Fe-based amorphous metal particles becomes insufficient. If the molding pressure exceeds 1000 MPa, the cost of the press molding apparatus and the mold increases.

  The atmosphere during the warm forming step is preferably a non-oxidizing atmosphere (an atmosphere having substantially very little oxygen, for example, in nitrogen or argon).

  Next, a strain relaxation heat treatment step is performed to relax the strain accumulated in the Fe-based amorphous metal powder in the compact. There is no particular limitation on the heating method in this step, and a known method can be used, but it is more preferable that the heating is performed by the same microwave heating as described above. The heat treatment temperature and time in the strain relaxation heat treatment step are not particularly limited unless the Fe-based amorphous metal particles are crystallized. Further, the atmosphere during the strain relaxation heat treatment step may be a non-oxidizing atmosphere or air.

  The powder magnetic core which concerns on this invention is obtained by the above manufacturing procedure.

(Inductance element / Rotating electric machine)
By utilizing the above-described dust core according to the present invention, it is possible to provide an inductance element and a rotating electrical machine that can be made smaller and more efficient than conventional ones. FIG. 1 is a schematic perspective view showing an example (choke coil) of an inductance element according to the present invention. FIG. 2 is a schematic perspective view showing another example (reactor) of the inductance element according to the present invention.

  As shown in FIG. 1, a choke coil 10 according to the present invention is obtained by winding a conductor wire 12 around a dust core 11 of the present invention, and terminals 13 are formed at both ends of the conductor wire 12. . The powder magnetic core 11 is an annular (so-called racetrack-like) continuous body, and the cross-sectional shape thereof may be square or circular. The choke coil 10 is used as a booster circuit for home appliances, for example.

  As shown in FIG. 2, a reactor 20 according to the present invention is obtained by winding a conductor wire 12 around a dust core 21 of the present invention, and terminals 13 are formed at both ends of the conductor wire 12. The dust core 21 has an annular shape, but has a structure in which two straight members 22 and two U-shaped members 23 are connected. The connection / fixation of the members may be performed with an adhesive (for example, a resin-based adhesive) or a mechanical jig (for example, a band). The reactor 20 is used, for example, as a booster circuit for a hybrid vehicle or solar power generation.

  The dust core 21 may use the dust core of the present invention as a whole (the straight member 22 and the U-shaped member 23), or use the dust core of the present invention for the straight member 22 in order to adjust the permeability. For the U-shaped member 23, a conventional dust core (for example, Fe-Si dust core, Fe-Al-Si dust core) may be used. In other words, the inductance element according to the present invention only needs to use the dust core of the present invention for a part thereof.

  Moreover, in a rotating electrical machine (for example, a motor), it is known that the magnetic characteristics of the stator and the rotor core greatly affect the efficiency of the rotating electrical machine. Since the dust core according to the present invention has excellent magnetic properties and high mechanical strength, it can be formed into a stator core or a rotor core having a desired shape. That is, by using the dust core of the present invention as a stator core or a rotor core of a rotating electrical machine, it is possible to reduce the size and increase the efficiency of the rotating electrical machine.

  The present invention will be described in more detail with reference to specific examples. However, the following examples show specific examples of the contents of the present invention, and the present invention is not limited to these examples.

[Experiment 1]
(Production of dust core)
Fe-Si-B amorphous metal powder (crystallization temperature T _x = 739 K) with a composition equivalent to 2605HB1 amorphous ribbon manufactured by Metglas, Inc. and prepared by water atomization method is prepared as Fe-based amorphous metal powder did. The amorphous metal powder was classified by sieving, and a powder having a particle size of 100 μm or less was used for the experiment. Next, polyether ether ketone (PEEK, melting point T _m = 613 K) is prepared as a resin binder. In addition to amorphous metal powder so as to be 10% by volume, a lab plast mill apparatus (made by Brabender, model: W50EHT) ). The obtained kneaded powder (aggregated by kneading) was crushed in a mortar to obtain granules having an average size of 0.5 mm or less.

  1.5 g of the crushed particles were put into a cemented carbide mold (outer diameter 13 mm, inner diameter 8 mm), and a warm forming process was performed with a hot press apparatus (manufactured by Tokyo Vacuum Co., Ltd., model: GP-2300). A time-temperature chart and a time-forming pressure chart in the warm forming step are shown in FIGS. 3A to 3B. As shown in FIG. 3A to FIG. 3B, the molding pressure was set to 800 MPa, the load was applied before the temperature increase, the temperature was increased to a predetermined molding temperature in 60 minutes, the temperature was maintained for 20 minutes after the temperature increase, and then immediately unloaded. The molding temperature was 533 to 693 K, and the atmosphere was nitrogen gas.

  The resulting compact (annular pellet with an outer diameter of 13 mm, an inner diameter of 8 mm, and a thickness of 3 mm) was subjected to a strain relaxation heat treatment process (held at 673 K in air for 1 hour) to obtain a dust core. . In addition, a commercially available Fe-based amorphous metal dust core was prepared as a comparative sample.

(Characteristic evaluation of dust core)
(1) Evaluation of space factor of Fe-based amorphous metal The cross-sectional structure of the produced dust core was observed with a scanning electron microscope (SEM, manufactured by Hitachi, Ltd., model: S-2380N). The space factor was calculated. The following formula was used to calculate the space factor of the Fe-based amorphous metal. The results are shown in Table 1 described later.
"Facing ratio of Fe-based amorphous metal (%) = (area of Fe-based amorphous metal in the field of view) / (area of field of view) x 100"
The “area of the visual field” is the total area of the observation image of one visual field of a microscope (for example, a scanning electron microscope or an optical microscope), and an area (enlarged) containing about 100 to 300 Fe-based amorphous metal particles. The magnification is preferably adjusted to about 200 to 500 times. Further, the “area of the Fe-based amorphous metal” can be obtained by, for example, image analysis of the observed image.

  FIG. 4A is an SEM observation image showing the used Fe-based amorphous metal powder (before warm forming), and FIG. 4B is an SEM observation image showing an example of a cross-sectional structure of the produced dust core. As shown in FIG. 4A, in the Fe-based amorphous metal powder before warm forming, individual particles include so-called spherical particles (not limited to true spheres but also distorted ellipsoids. Most of the surface is outside. It can be seen that the particles are composed of convex curved surfaces. On the other hand, as shown in FIG. 4B, in the powder magnetic core according to the present invention (for example, the space factor of Fe-based amorphous metal is 85% or more), the originally spherical amorphous metal particles are plastically deformed. It was clearly observed that there was a region in which the interface between two adjacent metal particles was parallel through a resin binder having a substantially constant thickness. In addition, residual voids were observed in the dust core.

  The presence or absence of plastic deformation of amorphous metal particles by SEM observation is also shown in Table 1 described later. For samples that were observed to be plastically deformed and that had an amorphous metal particle space factor of more than 80%, “exist” was indicated. For samples that did not show plastic deformation within the observed range, Was written as “nothing”.

(2) Evaluation of mechanical strength The mechanical strength of the produced dust core was evaluated. In the present invention, the crushing strength was measured as an index of mechanical strength. The crushing strength was measured according to the sintered bearing-crushing strength test method (JIS Z 2507). The crushing strength is given by “K = F (De) / (L · e ² )”. K is the crushing strength (unit: MPa), F is the maximum load at break (unit: N), L is the thickness of the annular pellet (unit: mm), D is the outer diameter of the annular pellet (unit: unit) mm) and e are the outer diameter / inner diameter difference (unit: mm) of the annular pellet. The results are also shown in Table 1 described later.

(3) Evaluation of magnetic properties The magnetic properties of the produced dust cores were evaluated. In this experiment, the magnetic flux density when a constant external magnetic field was applied was measured as an index of magnetic characteristics. The magnetic flux density was measured using a sample vibration magnetometer (VSM), and the magnetic flux density at an applied magnetic field of 10,000 Oe (about 795800 A / m) was expressed as “B ₁₀₀ ” (unit: T). The results are also shown in Table 1 described later.

  FIG. 5 is a graph showing the relationship between the space factor of the Fe-based amorphous metal and the molding temperature in the dust core of Experiment 1. As shown in FIG. 5 and Table 1, the space factor of the Fe-based amorphous metal powder increases as the molding temperature rises, and the desired densification (space factor 80) is achieved at a molding temperature of about 563 K or higher. It was confirmed that further desired densification (space factor 85% or more) was obtained at a molding temperature of about 603 K or more. The space factor reached a maximum at 613 K, which is the melting point of PEEK, and decreased slightly above the melting point, but a substantially constant value was obtained up to a molding temperature of 693 K.

The conventional amorphous metal dust core (commercially available) has a space factor of about 70%, a crushing strength of about 10 to 20 MPa, a magnetic flux density (B ₁₀₀ ) of about 0.4 T, and iron loss ( W _{1 / 10k} ) was about 100 kW / m ³ . The iron loss will be described later.

As shown in Table 1, a commercially available dust core is made of 2605HB1 equivalent water atomized powder and PEEK, and plastic deformation of the amorphous metal powder was observed. (Corresponding to the embodiment of the present invention), it is demonstrated that the crushing strength is improved by about 2.5 times or more and the magnetic flux density (B ₁₀₀ ) is improved by about 1.5 times or more compared to the commercially available dust core. It was. In addition, the sample (corresponding to the comparative example in the present invention) in which the plastic deformation of the amorphous metal powder could not be confirmed was higher than the characteristics of the commercially available product, but the degree was small and did not reach the expected level. .

[Experiment 2]
(Production of dust core)
Fe-Si-B amorphous metal powder (crystallization temperature T _x = 739 K) and KUAMET (registered trademark, Epson Atomic) manufactured by the water atomization method and having a composition equivalent to 2605HB1 amorphous ribbon as Fe-based amorphous metal powder Manufactured by Susu Co., Ltd., and a crystallization temperature T _x = 813 K) was prepared. The amorphous metal powder was classified by sieving, and a powder having a particle size of 100 μm or less was used for the experiment. As resin binders, PEEK (melting point T _m = 613 K), polyphenylene sulfide (PPS, melting point T _m = 563 K) and polyamide 66 (PA 66, melting point T _m = 538 K) were prepared. Except for these, a dust core was produced in the same manner as in Experiment 1.

  In the case of using a water atomized powder having a composition equivalent to 2605HB1 as the Fe-based amorphous metal, the molding temperature was 613 to 693 K, and the strain relaxation heat treatment after compacting was held at 673 K in the atmosphere for 1 hour. In the case of using KUAMET (registered trademark) as the Fe-based amorphous metal, the molding temperature was 693 to 773 K, and the strain relaxation heat treatment after compacting was held at 698 K in the atmosphere for 3 hours. Table 2 shows the specifications of the dust core.

(Characteristic evaluation of dust core)
As in Experiment 1, the space factor and mechanical strength of the Fe-based amorphous metal were evaluated on the produced powder magnetic core of Experiment 2. For the evaluation of magnetic properties, iron loss was measured in this experiment. The iron loss was measured using a BH analyzer (manufactured by Iwadori Measurement Co., Ltd.), and the iron loss at 10 kHz in 0.1 T was expressed as “W _{1 / 10k} ” (unit: kW / m ³ ). The results are also shown in Table 2.

In addition, as a comprehensive evaluation, those satisfying all of “space factor over 80%”, “crushing strength over 20 MPa” and “iron loss less than 100 kW / m ³ ” are evaluated as “pass” and all Those that could not be satisfied were evaluated as “failed”. The results are also shown in Table 2.

As shown in Table 2, since the warm forming conditions of Experiment 2 were all “T / T _x ≧ 0.75”, the space factor of the Fe-based amorphous metal exceeded 80% in all samples. became. When T _m / T _x is within the range specified in the present invention (T _m / T _x ≧ 0.70), Fe-based amorphous metal particles can be plastically deformed without thermally deteriorating the resin binder. Thus, a dust core having a magnetic property superior to that of a commercially available dust core and high mechanical strength was obtained, and the overall evaluation was “pass” (that is, equivalent to an example of the present invention). On the other hand, when T _m / T _x is outside the range specified in the present invention, since the resin binder starts to thermally deteriorate, the mechanical strength and / or magnetic properties are equal to or less than those of commercially available dust cores. The overall evaluation was “failed” (that is, equivalent to a comparative example in the present invention).

In addition, the molding temperature T = 773 K in KUAMET (registered trademark) is “T / T _x = 773/813 = 0.9507…” and rounded off to the second decimal place, it is regarded as “T / T _x = 0.95” Can do. Further, since the resin binder has a higher thermal expansion coefficient (about one digit higher) than that of the Fe-based amorphous metal, a tendency that the space factor of the Fe-based amorphous metal decreases as the molding temperature increases is observed.

  In more detail, when water atomized powder with a composition equivalent to 2605HB1 is used as the Fe-based amorphous metal, any resin binder can provide better magnetic properties and higher mechanical strength than commercially available dust cores. Was confirmed.

  When KUAMET (registered trademark) was used as the Fe-based amorphous metal, it was confirmed that when PEEK was used as the resin binder, magnetic properties superior to commercially available powder magnetic cores and high mechanical strength were obtained. This was thought to be due to the high heat resistance of PEEK (the thermal decomposition temperature of PEEK was about 773 K). In addition, since the sample with a molding temperature of 773 K using PEEK was close to the thermal decomposition temperature, there was a tendency for the crushing strength to decrease and the iron loss to increase compared to other examples.

  On the other hand, samples using KUAMET (registered trademark) as the Fe-based amorphous metal and PPS or PA66 as the resin binder had mechanical strength and / or magnetic properties equivalent to or lower than those of commercially available dust cores. . This was thought to be due to thermal degradation of the resin binder because PPS and PA66 had lower heat resistance than PEEK. In addition, since the volume of the resin binder decreases with the thermal decomposition of the resin binder, in these samples, the tendency for the space factor of the Fe-based amorphous metal to increase with increasing molding temperature was observed.

[Experiment 3]
(Production of dust core)
2605HB1 amorphous ribbon ground powder (average particle size 100μm, 75% by mass) and AW2-08 (Epson Atmix Co., Ltd., crystallization temperature T _x ) so that the particle size distribution of Fe-based amorphous metal powder is bimodal. = 813 K, average particle size 6 μm, 25 mass%). PEEK was used as a resin binder and added to the mixed powder so as to be 0.5 to 16% by volume. The molding temperature in the warm molding process was 673 K. Except for these, a dust core was produced in the same manner as in Experiment 1.

The pulverized powder of 2605HB1 is obtained by pulverizing 2605HB1 amorphous ribbon (thickness 25 μm), and the average particle diameter is an average value of lengths in the longitudinal direction when the pulverized powder is observed with an electron microscope. In the present invention, when a mixture of a plurality of amorphous metal powder, the lowest crystallization temperature of the mixed amorphous metal powders, and the crystallization temperature T _x of the mixed powder. Similarly, when a plurality of resin binders are mixed, the lowest melting point of the mixed resin binders is set as the melting point T _{m of the} mixed binder.

That is, in Experiment 3, “T _m / T _x = 0.83” and “T / T _x = 0.91”. Other specifications of the produced dust core are shown in Table 3 described later.

(Characteristic evaluation of dust core)
In the same manner as in Example 1, the space factor of the Fe-based amorphous metal and the mechanical strength were evaluated on the powder magnetic core of Experiment 3 produced. Regarding the evaluation of magnetic properties, both magnetic flux density evaluation and iron loss evaluation were performed in this experiment. The results are also shown in Table 3.

  As shown in Table 3, when mixing amorphous metal powders with different particle sizes and mixing a resin binder in the range of 1 to 15% by volume, the space factor is reduced compared with the case where the molding temperature is set to 673 K in Experiment 1. It was confirmed that it was further enhanced (that is, equivalent to an embodiment of the present invention). From this result, even when multiple types of Fe-based amorphous metal powders with different crystallization temperatures are mixed, the density can be increased by plastic deformation of the Fe-based amorphous metal with the lowest crystallization temperature. I found out.

  In more detail, when the amount of PEEK added is 16% by volume, the iron loss is low, but the space factor of the Fe-based amorphous metal is 80% or less, and as a result, the magnetic flux density is greatly reduced (the present invention). Equivalent to the comparative example). On the other hand, when the amount of PEEK added is 0.5% by volume, the space factor of the Fe-based amorphous metal is high, the crushing strength and the magnetic flux density are high, but the iron loss is greatly increased (corresponding to the comparative example in the present invention) . This was thought to be because the amount of resin binder added was too small to ensure sufficient electrical insulation between the amorphous metal particles, and eddy current loss increased.

[Experiment 4]
In this experiment, an experiment / evaluation using microwave heating was performed as a method of strain relaxation heat treatment after the warm forming process. The 2.45 GHz single mode furnace was used as the heating device, and the dust core was heated in a magnetic field. The initial output of the microwave is 0.7 kW, the target temperature of the dust core using water atomized powder of 2605HB1 equivalent composition as Fe-based amorphous metal is 673 K, the target temperature of the dust core using KUAMET (registered trademark) is 698 K. The holding time was 20 minutes. The temperature was measured using a radiation thermometer (manufactured by Chino Co., Ltd., model: IR-CAI).

  As a result of the experiment, rapid heating at 20 to 30 ° C./s was possible simultaneously with microwave irradiation in any sample. Furthermore, in the heat treatment by microwave heating, even when held for 20 minutes, the iron loss could be reduced as in the case of holding for 1 to 3 hours by radiant heating. That is, it was confirmed that the heat treatment using a microwave as a heat source can shorten the treatment time to 1/3 or less compared with the conventional radiation heating.

  Note that the above-described embodiments have been specifically described in order to help understanding of the present invention, and the present invention is not limited to having all the configurations described. For example, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, a part of the configuration of each embodiment can be deleted, replaced with another configuration, or added with another configuration.

10 ... Choke coil, 11 ... Dust core, 12 ... Conductor wire, 13 ... Terminal,
20 ... reactor, 21 ... dust core, 22 ... straight member, 23 ... U-shaped member.

Claims (7)

A powder magnetic core mainly composed of powder composed of spherical particles of Fe-based amorphous metal and a resin binder, and formed by warm molding,
The resin binder is one of polyetheretherketone, polyphenylene sulfide and polyamide 66,
The Fe-based amorphous metal includes Fe-Si-B-Cr-C amorphous metal, Fe-Si-B-Co amorphous metal, and Fe-Si-B-Cu- having a crystallization temperature T _x (K) of 763 K or less. is either Nb amorphous metal, and the relationship between the melting point T _m (K) of the resin binder is a T _m / T _x ≧ 0.70,
In the dust core, the spherical particles of the Fe-based amorphous metal powder are pressed against each other and plastically deformed by the warm forming. As a result, the interfaces between the two adjacent spherical particles are parallel to each other through the resin binder. It forms a space made, as a result, the Fe-based amorphous metal powders space factor of is not less than 80 percent 99 percent, the iron loss Ri 70 kW / m ³ der hereinafter sintered bearing - A dust core having a crushing strength of more than 20 MPa when crushing strength is measured according to a crushing strength test method . An inductance element using a dust core,
The inductance element according to claim 1, wherein at least a part of the dust core is the dust core according to claim 1 . The inductance element according to claim 2 ,
The inductance element is a reactor or a choke coil. A rotary electric machine using a dust core,
The rotating electrical machine, wherein at least a part of the dust core is the dust core according to claim 1 . In the rotating electrical machine according to claim 4 ,
The rotating electrical machine characterized in that the dust core is a stator core and / or a rotor core. A method for producing a powder magnetic core mainly composed of a powder composed of spherical particles of Fe-based amorphous metal and a resin binder,
The resin binder is one of polyetheretherketone, polyphenylene sulfide and polyamide 66,
The Fe-based amorphous metal includes Fe-Si-B-Cr-C amorphous metal, Fe-Si-B-Co amorphous metal, and Fe-Si-B-Cu- having a crystallization temperature T _x (K) of 763 K or less. Nb amorphous metal, and the relationship with the melting point T _m (K) of the resin binder is T _m / T _x ≧ 0.70,
A resin coating step of mixing the resin binder with the Fe-based amorphous metal powder in a range of 1% by volume to 15% by volume and coating the resin binder on the surface of the spherical particles of the Fe-based amorphous metal powder. When,
Warm forming step in which the Fe-based amorphous metal powder is coated with the resin binder and the Fe-based amorphous metal is softened and a molded body is formed at a predetermined temperature and a predetermined pressure equal to or higher than the melting point of the resin binder. When,
A strain relaxation heat treatment step for relaxing strain accumulated in the Fe-based amorphous metal powder in the molded body ,
Before SL warm forming step, the is a predetermined temperature or less 0.75 Ultra 0.95 and 693 K of the crystallization temperature, the is a predetermined pressure 1000 MPa inclusive 500 MPa, the Fe-based amorphous metal powders The spherical particles are pressed against each other and plastically deformed to form a region in which the interface between two adjacent spherical particles is parallel via the resin binder, and the Fe-based amorphous metal in the molded body It is a process to make the space factor of the powder more than 80% and 99% or less,
As a result, the powder magnetic core has an iron loss of 70 kW / m ³ or less, and when the crushing strength is measured in accordance with the sintered bearing-crushing strength test method, the crushing strength exceeds 20 MPa. A method for producing a dust core, characterized in that: In the manufacturing method of the powder magnetic core according to claim 6 ,
A method of manufacturing a dust core, wherein the heating in the warm forming step and / or the strain relaxation heat treatment step is performed by microwave heating.

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